1. Field of the Invention
The present invention relates to an organic EL [electroluminescence] device (organic EL display, organic EL light and the like).
2. Description of Related Art
An organic EL display is composed of mainly a panel portion, a source driver, and a gate driver. The panel portion includes pixel circuits whose number is equal to the number of pixels (the number of effective pixels in a color XGA [extended graphics aray]: 1024 lateral×768 vertical×3 colors). The pixel circuit is composed of a transistor and an organic EL element. The transistor is controlled to flow a desired drive current into the organic EL element, whereby it is possible to make the organic EL element emit light. The drive current flowing in the organic EL element and the brightness of the organic EL element are in a proportional relationship.
In the meantime, as examples of prior art relevant to the above description, there are JP-A-2003-330419 and JP-A-2005-157009.
The transistor included in the pixel circuit has a temperature characteristic and production unevenness, and the drive current flowing in the organic EL element varies under the influence of these; accordingly, it is hard to keep the brightness of the organic EL element constant.
In the meantime, conventionally, a structure is employed, in which various kinds of calculations and the like are performed based on temperature information obtained by a temperature sensor to correct a control voltage of the transistor; whereby the desired drive current is flowed into the organic EL element irrespective of the temperature to keep the brightness of the organic EL element at a desired value.
However, in the above conventional structure, the temperature sensor is necessary and an analog signal obtained by the temperature sensor is converted into a digital signal to perform a complicated logic calculation by means of a data table and the like.